Tea is a sun-loving leaf and unlike the delicate coffee flowers that bear fruit, leaves are tough little photosynthetic factories that thrive in warming regions of the world.
So long as rains remain steady, a longer growing season and greater solar intensity will increase yield, but as with most good things, too much can be bad, according to Aziz Elbehri, senior economist at the United Nations’ Food and Agriculture Organization (FAO).
Elbehri addressed attendees Sept. 15 at COTECA16 (the Coffee, Tea and Cocoa Show) in Hamburg, Germany. The event, which showcased the offerings of 200 exhibitors, drew 3,600 tea and coffee professionals to the North Sea port where much of the tea destined for Europe is landed.
Earth scientists recently announced the Anthropocene era to describe the current geological age during which human activity has been the dominant influence on climate and the environment. Farmers globally must now contend with accelerating temperatures that in 2016 set 11 dating to October of last year. Last month, for example, was the hottest August in 136 years.
Dr. Henriette Walz
Dr. Henriette Walz, climate change and environmental expert with UTZ Certified, reported that by 2050 total global coffee growing areas will be reduced by 50% due to climate change, with production moving away from the equator. Continued temperature increases of 4.8°C would make wild coffee extinct by 2100, she said.
Walz cited the observations of a coffee grower who complained that “Climate change compromises us three times: We face higher production costs because of more frequent pests and diseases; we have to work more because of erratic flowering and ripening; and, we get lower prices because of lower quality due to higher temperatures.”
The impact of rising temperatures is less dire for tea growers.
Working closely with the Tea Research Foundation in Kenya, FAO conducted a two-year assessment of the impact of climate change on tea, explained Elbehri. Researchers discovered a “significant relationship between tea yield and rising temperature as long as soil moisture is not limiting.”
“Preliminary results suggest that the suitability of tea growing areas [in Kenya] is expected to increase 8% by 2025, and then drop by 22.5% during the 50 years ending 2075,” according to Elbehri. Projections through 2075 indicate current tea-growing areas in Kenya would decrease not because of decreasing rainfall amounts but due to mean air temperatures exceeding a threshold of 23.5°C.
Temperatures are rising as rainfall declines at Kangaita, Kenya. Source: FAO/Tea Research Foundation (2013).
Intense sunlight increased biomass at the Timbilil Tea Estate where field studies were conducted. Rising temperatures reduced stress due to cold, he explained, but once temperatures exceed the threshold the impact is catastrophic due to the combination of heat, proliferation of pests and disease. Planting tea under shade trees and within the forest canopy can reduce loss but tea trees simply cannot tolerate high heat sustained over long periods.
The study also included the results of 700 surveys completed by farmers in Kenya’s seven tea-growing regions: 43.1% of growers reported fluctuations in rainy and dry seasons have forced them to shift their traditional planting and harvesting dates. Growers (35.6%) also reported challenging frost conditions and unusual hail, often followed by extended drought (34.6%). In Kericho, Sotik, and the Nandi Hill regions, large estates report an estimated 2.7 million kilos of tea is lost to hail. Kenya traditionally experiences three months of reduced rainfall between December and March, but growing conditions in the past two decades have become unpredictable. Producers estimated a loss of up to 30% in cash earnings due to climate variability, said Elbehri. To cope, farmers are growing drought-resistant varieties, diversifying their crops, and planting shade trees.
Tea is a rural-based enterprise with 65% of the crop produced by smallholders. Three million Kenyans directly and indirectly rely on tea, which contributes 4% of the country’s gross revenue.
Elbehri also pointed out that researchers explored the generation of CO2 per cup. Tea cultivation and production accounted for only 20% of the 24-gram total. Transportation added another 4% but 75% of the CO2 is generated by consumers preparing their tea.
Climate Change Impact Assessment: Analysis of links between climate variables and tea production in Kenya.